The previous owner had installed Hurst shifter. It looked very nice, but ruined the gear shifts and produced a lot of noise. A loud metallic rattle that increased with engine revs.
First, second and third try
- FatMat accoustic mat on the center tunnel
- Driveshaft rubber boot (the Hurst shifter makes away with the stock rubber boot)
- Anti-venom mod
- The gearbox has a detent ball spring assembly to provide artificial resistance when selecting a gear, partly also to prevent the gearbox to "pop out" of gear. By shimming the ball spring, the resistance is reduced)
This helped to quiet down the noise somewhat, as the higher pitched metallic rattle was reduced. The effort to engage gears was reduced to an acceptable level by the anti-venom mod, but the cross gate movement was still too heavy due to the shorter throw of the Hurst shifter.
Update! Don't put FatMat on the center tunnel. It melts and creates a mess.
If at First, Second, and Third You Don't Succeed
The C6 shifter re-introduces the noise cancellation designed by GM - and removed the Hurst rattle. Finally. The C6 gear knob is also shifted towards the driver, providing better ergonomics and smoother gear shifts. I could still notice a slight rattle if I wanted to...
Root cause
The true origin of the rattle was a bad harmonic balancer! This causes engine vibrations, which are not cancelled out by the Hurst shifter design. I could still notice a slight vibration in the C6 shifter, but at 101.000 miles, the balancer was replaced while repairing a front oil seal leak, and the C6 shifter went completely silent (along with the rest of the drivetrain, which also quieted down at higher RPMs).